dm: core: Allow parents to have platform data for their children

For buses it is common for parents to need to know the address of the child
on the bus, the bus speed to use for that child, and other information. This
can be provided in platform data attached to each child.

Add driver model support for this, including auto-allocation which can be
requested using a new property to specify the size of the data.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

drivers/core/device-remove.c

@@ -92,6 +92,10 @@ int device_unbind(struct udevice *dev)
 		free(dev->platdata);
 		dev->platdata = NULL;
 	}
+	if (dev->flags & DM_FLAG_ALLOC_PARENT_PDATA) {
+		free(dev->parent_platdata);
+		dev->parent_platdata = NULL;
+	}
 	ret = uclass_unbind_device(dev);
 	if (ret)
 		return ret;

drivers/core/device.c

@@ -80,6 +80,18 @@ int device_bind(struct udevice *parent, struct driver *drv, const char *name,
 			goto fail_alloc1;
 		}
 	}
+	if (parent) {
+		int size = parent->driver->per_child_platdata_auto_alloc_size;
+
+		if (size) {
+			dev->flags |= DM_FLAG_ALLOC_PARENT_PDATA;
+			dev->parent_platdata = calloc(1, size);
+			if (!dev->parent_platdata) {
+				ret = -ENOMEM;
+				goto fail_alloc2;
+			}
+		}
+	}
 
 	/* put dev into parent's successor list */
 	if (parent)
@@ -107,8 +119,12 @@ fail_bind:
 			dev->name);
 	}
 fail_uclass_bind:
-	if (parent)
 	list_del(&dev->sibling_node);
+	if (dev->flags & DM_FLAG_ALLOC_PARENT_PDATA) {
+		free(dev->parent_platdata);
+		dev->parent_platdata = NULL;
+	}
+fail_alloc2:
 	if (dev->flags & DM_FLAG_ALLOC_PDATA) {
 		free(dev->platdata);
 		dev->platdata = NULL;
@@ -247,6 +263,16 @@ void *dev_get_platdata(struct udevice *dev)
 	return dev->platdata;
 }
 
+void *dev_get_parent_platdata(struct udevice *dev)
+{
+	if (!dev) {
+		dm_warn("%s: null device", __func__);
+		return NULL;
+	}
+
+	return dev->parent_platdata;
+}
+
 void *dev_get_priv(struct udevice *dev)
 {
 	if (!dev) {

include/dm/device.h

@@ -26,6 +26,9 @@ struct driver_info;
 /* DM should init this device prior to relocation */
 #define DM_FLAG_PRE_RELOC	(1 << 2)
 
+/* DM is responsible for allocating and freeing parent_platdata */
+#define DM_FLAG_ALLOC_PARENT_PDATA	(1 << 3)
+
 /**
  * struct udevice - An instance of a driver
  *
@@ -46,6 +49,7 @@ struct driver_info;
  * @driver: The driver used by this device
  * @name: Name of device, typically the FDT node name
  * @platdata: Configuration data for this device
+ * @parent_platdata: The parent bus's configuration data for this device
  * @of_offset: Device tree node offset for this device (- for none)
  * @of_id: Pointer to the udevice_id structure which created the device
  * @parent: Parent of this device, or NULL for the top level device
@@ -65,6 +69,7 @@ struct udevice {
 	struct driver *driver;
 	const char *name;
 	void *platdata;
+	void *parent_platdata;
 	int of_offset;
 	const struct udevice_id *of_id;
 	struct udevice *parent;
@@ -146,6 +151,9 @@ struct udevice_id {
  * device_probe_child() pass it in. So far the use case for allocating it
  * is SPI, but I found that unsatisfactory. Since it is here I will leave it
  * until things are clearer.
+ * @per_child_platdata_auto_alloc_size: A bus likes to store information about
+ * its children. If non-zero this is the size of this data, to be allocated
+ * in the child's parent_platdata pointer.
  * @ops: Driver-specific operations. This is typically a list of function
  * pointers defined by the driver, to implement driver functions required by
  * the uclass.
@@ -165,6 +173,7 @@ struct driver {
 	int priv_auto_alloc_size;
 	int platdata_auto_alloc_size;
 	int per_child_auto_alloc_size;
+	int per_child_platdata_auto_alloc_size;
 	const void *ops;	/* driver-specific operations */
 	uint32_t flags;
 };
@@ -184,6 +193,16 @@ struct driver {
 void *dev_get_platdata(struct udevice *dev);
 
 /**
+ * dev_get_parent_platdata() - Get the parent platform data for a device
+ *
+ * This checks that dev is not NULL, but no other checks for now
+ *
+ * @dev		Device to check
+ * @return parent's platform data, or NULL if none
+ */
+void *dev_get_parent_platdata(struct udevice *dev);
+
+/**
  * dev_get_parentdata() - Get the parent data for a device
  *
  * The parent data is data stored in the device but owned by the parent.

test/dm/bus.c

@@ -9,11 +9,16 @@
 #include <dm/device-internal.h>
 #include <dm/root.h>
 #include <dm/test.h>
+#include <dm/uclass-internal.h>
 #include <dm/ut.h>
 #include <dm/util.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
+struct dm_test_parent_platdata {
+	int count;
+};
+
 enum {
 	FLAG_CHILD_PROBED	= 10,
 	FLAG_CHILD_REMOVED	= -7,
@@ -62,6 +67,8 @@ U_BOOT_DRIVER(testbus_drv) = {
 	.priv_auto_alloc_size = sizeof(struct dm_test_priv),
 	.platdata_auto_alloc_size = sizeof(struct dm_test_pdata),
 	.per_child_auto_alloc_size = sizeof(struct dm_test_parent_data),
+	.per_child_platdata_auto_alloc_size =
+			sizeof(struct dm_test_parent_platdata),
 	.child_pre_probe = testbus_child_pre_probe,
 	.child_post_remove = testbus_child_post_remove,
 };
@@ -271,3 +278,77 @@ static int dm_test_bus_parent_ops(struct dm_test_state *dms)
 	return 0;
 }
 DM_TEST(dm_test_bus_parent_ops, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that the bus can store platform data about each child */
+static int dm_test_bus_parent_platdata(struct dm_test_state *dms)
+{
+	struct dm_test_parent_platdata *plat;
+	struct udevice *bus, *dev;
+	int child_count;
+
+	/* Check that the bus has no children */
+	ut_assertok(uclass_find_device(UCLASS_TEST_BUS, 0, &bus));
+	device_find_first_child(bus, &dev);
+	ut_asserteq_ptr(NULL, dev);
+
+	ut_assertok(uclass_get_device(UCLASS_TEST_BUS, 0, &bus));
+
+	for (device_find_first_child(bus, &dev), child_count = 0;
+	     dev;
+	     device_find_next_child(&dev)) {
+		/* Check that platform data is allocated */
+		plat = dev_get_parent_platdata(dev);
+		ut_assert(plat != NULL);
+
+		/*
+		 * Check that it is not affected by the device being
+		 * probed/removed
+		 */
+		plat->count++;
+		ut_asserteq(1, plat->count);
+		device_probe(dev);
+		device_remove(dev);
+
+		ut_asserteq_ptr(plat, dev_get_parent_platdata(dev));
+		ut_asserteq(1, plat->count);
+		ut_assertok(device_probe(dev));
+		child_count++;
+	}
+	ut_asserteq(3, child_count);
+
+	/* Removing the bus should also have no effect (it is still bound) */
+	device_remove(bus);
+	for (device_find_first_child(bus, &dev), child_count = 0;
+	     dev;
+	     device_find_next_child(&dev)) {
+		/* Check that platform data is allocated */
+		plat = dev_get_parent_platdata(dev);
+		ut_assert(plat != NULL);
+		ut_asserteq(1, plat->count);
+		child_count++;
+	}
+	ut_asserteq(3, child_count);
+
+	/* Unbind all the children */
+	do {
+		device_find_first_child(bus, &dev);
+		if (dev)
+			device_unbind(dev);
+	} while (dev);
+
+	/* Now the child platdata should be removed and re-added */
+	device_probe(bus);
+	for (device_find_first_child(bus, &dev), child_count = 0;
+	     dev;
+	     device_find_next_child(&dev)) {
+		/* Check that platform data is allocated */
+		plat = dev_get_parent_platdata(dev);
+		ut_assert(plat != NULL);
+		ut_asserteq(0, plat->count);
+		child_count++;
+	}
+	ut_asserteq(3, child_count);
+
+	return 0;
+}
+DM_TEST(dm_test_bus_parent_platdata, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);